Flexible tubular pipe with an internal impervious polymeric sheath

Abstract

It is of the type comprising at least, from the interior towards the exterior, an internal non-impervious metal carcass (1), the exterior surface of which has interstices (9), an internal impervious polymeric sheath (2), a set of layers of reinforcement wires (3) (4), and an external protection sheath (5), and is characterized in that said internal impervious polymeric sheath (2) mainly comprises a thermoplastic polymer part associating at least two fluoromonomers, at least one of said fluoromonomers carrying at least one alkoxy group, the thermoplastic polymer part being blistering-resistant at a temperature of at least 130° C.

I claim: 
     
       1. Flexible tubular pipe of the type comprising at least, from the interior towards the exterior, an internal non-impervious metal carcass (1), an internal impervious polymeric sheath (2), a set of layers of reinforcement wires (3) (4), and an external protection sheath (5), the internal carcass (1) comprising at least one helically-wound profiled member with the turns clipped together so that at least the exterior surface of said internal carcass has interstices (9) between consecutive turns, said internal impervious polymeric sheath (2) being in the form of a continuous tubular layer and comprising a thermoplastic polymer part associating at least two fluoromonomers, characterized in that at least one of said fluoro monomers carries at least one alkoxy group, said thermoplastic polymer part being resistant to blistering at a temperature of at least 130° C. 
     
     
       2. Pipe according to claim 1 characterized in that the thermoplastic polymer constitutes the main part of the internal impervious sheath (1) and comprises at least one fluoromonomer and less than 50% of a perfluoromonomer carrying at least one alkoxy group. 
     
     
       3. Pipe according to claim 1 characterized in that the thermoplastic polymer associates a perfluoro(alkyl vinyl ether) with at least one fluoromonomer. 
     
     
       4. Pipe according to claim 3 characterized in that the perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether). 
     
     
       5. Pipe according to claim 3 characterized in that the perfluoro(alkyl vinyl ether) is perfluoro(ethyl vinyl ether). 
     
     
       6. Pipe according to claim 1 characterized in that the thermoplastic polymer associates at least 50% of tetrafluoroethylene (TFE) with at least one other fluoromonomer, at least one of said other fluoromonomers carrying at least one alkoxy group. 
     
     
       7. Pipe according to claim 1 characterized in that the thermoplastic polymer associates a cyclic fluoromonomer with at least one other fluoromonomer, at least one of said other fluoromonomers carrying at least one alkoxy group. 
     
     
       8. Pipe according to claim 1 characterized in that said thermoplastic polymer associates an anhydride fluoromonomer with at least one other fluoromonomer, at least one of said other fluoromonomers carrying at least one alkoxy group. 
     
     
       9. Pipe according to claim 1 characterized in that at least one of the fluoromonomers associated to constitute said thermoplastic polymer is a cyclic ether. 
     
     
       10. Pipe according to claim 6 characterized in that said thermoplastic polymer associates at least 70% of TFE with at least one other fluoromonomer, at least one of said other fluoromonomers carrying at least one alkoxy group. 
     
     
       11. Pipe according to claim 10 characterized in that the thermoplastic polymer is the type of material sold under the tradename PFA. 
     
     
       12. Pipe according to claim 1 characterized in that the thermoplastic polymer is a terpolymer associating two fluoromonomers one at least of which carries at least one alkoxy group with a relatively small proportion of a third fluoromonomer. 
     
     
       13. Pipe according to claim 12 characterized in that the third fluoromonomer is vinylidene fluoride (VF2). 
     
     
       14. Pipe according to claim 12 characterized in that the third fluoromonomer is chlorotrifluoroethylene (CTFE). 
     
     
       15. Pipe according to claim 12 characterized in that the terpolymer associates two fluoromonomers each carrying at least one alkoxy group with another fluoromonomer. 
     
     
       16. Pipe according to claim 1 characterized in that the thermoplastic polymer is semi-crystalline. 
     
     
       17. Pipe according to claim 1 characterized in that the thermoplastic polymer is crosslinked and has a crystalinity close to that corresponding to the non-crosslinked state, the crosslinking being operative in the amorphous phase. 
     
     
       18. Pipe according to claim 1 characterized in that the thermoplastic polymer is crosslinked and has a crystalinity lower than that of the non-crosslinked state. 
     
     
       19. Pipe according to claim 1 characterized in that the thermoplastic polymer has a bending stiffness greater than or equal to 50 MPa and preferably greater than or equal to 100 MPa for the maximal intended temperature of use, which temperature can be at least 130° C. and preferably at least 150° C., the bending stiffness being less than or equal to 2 500 MPa for the lowest intended ambient temperature, which temperature can be equal to or less than -20° C. and preferably to -40° C. 
     
     
       20. Pipe according to claim 1 characterized in that the internal impervious polymeric sheath (1) has an internal part (7) in a preferably amorphous polymer and resting on the internal carcass (1) inside said thermoplastic polymer main part. 
     
     
       21. Pipe according to claim 20 characterized in that the internal part constitutes a preferably continuous tubular layer made of an amorphous thermoplastic fluoropolymer having a high creep resistance, the thickness of said internal layer preferably being small, in the order of 0.5 mm to 3 mm. 
     
     
       22. Pipe according to claim 21 characterized in that the amorphous thermoplastic fluoropolymer is a copolymer or a terpolymer associating at least TFE and another fluoromonomer, preferably a cyclic fluoro ether or a fluoro aldehyde. 
     
     
       23. Pipe according to claim 20 characterized in that the internal part is made of a thermoplastic or non-thermoplastic elastomer having a relatively low bending stiffness compared to the thermoplastic polymer constituting the main part of the polymeric sheath, said internal part preferably being in the form of a band helically wound along the interstices (9) of the internal carcass (1) and penetrating at least partially into said interstices (9).